I am not exactly sure where this blood is coming from?

I am on Gildess Fe 1/20 which I believe is the generic for Loestrin 24 Fe. I have been on this for over a year, maybe two; However, my refill ran out a few weeks ago, so I had my week of sugar pills and then had to take another week off waiting for my new packs to come in, and then started over that Sunday. (So two weeks not taking white pills vs the usual one week) On the Friday before that Sunday that I restarted my pills I had sex as well as a few days ago while on the pill. We used condoms but I know that's never 100%.

A few days ago, after sex, we realized that I had bled... a decent amount. I am not due to be on my period nor did I really hurt anywhere. I also noticed it today while using the bathroom, but wasn't really enough to show up on a tampon or pantyliner for the rest of the day.

Could this be spotting from re-starting my birth control, pregnancy, or some other issue? I'm just really unsure. And what would you recommend doing if it continues? Thanks in advance for your help.